The Collaborative International Dictionary of English v.0.48:

Oxalyl \Ox"a*lyl\, n. [Oxalic + -yl.] (Chem.)
   (a) A hydrocarbon radical (C2O2) regarded as a residue of
       oxalic acid and occurring in derivatives of it.
   (b) An old name for carbonyl.
   (c) An old name for carboxyl.
       [1913 Webster]